Before you buy a smart thermostat, take a look at the valve on your radiator. Most valves take the new head directly. Some need an adapter, and not every system includes it.
The standard case: M30×1.5
Most radiator valves have an M30×1.5 thread. That means a 30 mm diameter and a 1.5 mm thread pitch. All smart thermostats fit these without an adapter. Typical manufacturers are Heimeier, Oventrop (newer valves), MNG, Honeywell/Braukmann, Junkers and Landis+Gyr.
If your old thermostat head shows one of these names, you usually do not need an adapter.
Danfoss: RA, RAV and RAVL
Danfoss valves are the most common special case. Here a smart thermostat needs an adapter. There are three common types: RA, RAV and RAVL.
Almost all systems include adapters for all three types. There are two exceptions:
- FRITZ!DECT 302 only includes an adapter for Danfoss RA.
- Bosch Radiator Thermostat II [+M] includes adapters for RA and RAVL, but not for RAV.
For Danfoss RA-N and RA 2000, Eve lists a separate adapter. Users report that the RA adapter sometimes fits.
M28×1.5, Caleffi and Giacomini
Valves with an M28×1.5 thread come from Herz, Comap or MMA, for example. Then there are valves from the Italian manufacturers Caleffi and Giacomini. Matching adapters are only included with three systems: Aqara W600, SwitchBot and Netatmo (Netatmo for M28 and Giacomini).
Old Oventrop valves: M30×1.0
Older Oventrop valves have a 30 mm diameter, but only a 1.0 mm thread pitch. A thermostat made for M30×1.5 will not screw on properly. Only Netatmo includes an adapter for these.
Which system includes which adapter
| System | Danfoss RA | RAV | RAVL | M28×1.5 | Caleffi | Giacomini | M30×1.0 |
|---|---|---|---|---|---|---|---|
| tado° X | check type | check type | check type | – | – | – | – |
| Homematic IP pure | yes | yes | yes | – | – | – | – |
| FRITZ!DECT 302 | yes | – | – | – | – | – | – |
| Bosch II [+M] | yes | – | yes | – | – | – | – |
| Eve Thermo | yes | yes | yes | – | – | – | – |
| Netatmo | yes | – | yes | yes | – | yes | yes |
| Aqara W600 | yes | yes | yes | yes | yes | yes | – |
| SwitchBot | yes | yes | yes | yes | yes | yes | – |
| Shelly BLU TRV | check type | check type | check type | – | – | – | – |
| SONOFF TRVZB | yes | yes | yes | – | – | – | – |
tado° X and Shelly BLU TRV come with several adapters. The manufacturer states exactly which types.
And if nothing fits?
For all other valves, such as old Vaillant valves, adapters are sold separately. They cost about €5–15 each. Factor that in if you have several radiators.
If you do not know which valve you have, go for a system with many adapters. Aqara W600 and SwitchBot each include six.
Tip for tenants
Swapping the thermostat head does not touch the heating system. Still, keep the old heads and screw them back on when you move out.